Signal repeater system



April 19, 1938. F. E. WELD 2,114,324

SIGNAL REPEATER SYSTEM Filed Feb. 14, 1933 3 Sheets-Shea?l l Juux..

3 Sheets-Sheet 2 F. E. WELD /alL T ff 51j SIGNAL REPEATER SYSTEM Filed Feb. 14, .1933

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April 19, 193s.

April 19, 1938. F. E. WELD 2,114,324

y SIGNAL REPEATER SYSTEM /nyen/or Patented Apr. 19, 1938 UNITED srA'rss SIGNAL REPEATER SYSTEM Foster E. Weld, Newton, Mass., assignorto The Gamewcll Company, Newton, Mass., a corporation of Massachusetts Application February 14, 1933, Serial No. 656,664

9 Claims.

The present invention relates to signaling systems, and more particularly to installations with several outer signal initiating circuits associated with one another, and with signal manifesting devices at a receiving station, by means of repeaters, which automatically organize the desired reception and manifestation of the signals originating in the outer circuits, each of which may comprise a group o-f individual signal despatch- 10- ing stations. Such installations are used for many purposes but mainly in re alarm systems with normally closed outer signal circuits or loops constantly carrying current, each loop comp-rising in series connection several so-called alarm boxes and also signal manifesting devices such as gongs and the like. Such systems must be necessarily as reliable and independent of supervision as possible, and it is for this reason desirable that the appliances involved be few, simple and rugged. However the repeaters are especially likely to be rather involved, cumbersome, and therefore expensive, and also unreliable because of their very complexity. It is therefore the main object of the present invention to provide a signaling system of the type referred to which is comparatively simple and inexpensive but nevertheless able securely and reliably to perform all functions legitimately required from such installations.

30 In its broader aspect the present invention proposes the interposition between a number of outer signaling circuits and a central reception circuit of selecting instrumentalities, .for example, of the type commonly used in automatic tele- 5 phone installations, which upon abnormal conditioning of any one outer circuit, associate the reception circuit with consecutive outer circuits, quickly passing from one normal circuit to the next, but being stopped for operative association lo between the reception, circuit and an abnormally conditioned outer circuit. This arrangement permits of various embodiments and elaborations, several of which are herein shown and described.

l5 In one modification the invention proposes arrangements for excluding accidentally faulty signal circuits from operative association with the signal reception devices, with the object of providing an installation always properly responsive 50 to signal circuits which are in good working condition, while preventing faulty circuits from interfering with the orderly reception of signals from sound circuits, this embodiment being particularly suited for central stations which are not 55 constantly supervised,

In another embodiment the invention employs instrumentalities for'preventing the unseparated consecutive reception of signal portions originating in different signal circuits, with the object of avoiding the misinterpretation of signals. 5

In still another variation the invention proposes the use of apparatus for quickly stopping the loop selecting means and for maintaining it stopped under certain conditions, with the object of providing an installation which securely estab- 10 lishes association between alarm and signal circuit, and which renders the repeater unresponsive in case of an accidentally defective signal circuit.

It is one of the features of the invention to l5 permit its use in so-called reflex circuit installations, that is, in circuits where signals originating in a certain outer signal circuit are not only received and repeated at the central station and in special manifesting or alarm circuits, but also reflexed into other outer signal circuits, excluding the circuit in which the signals originate. Such reiiexing into other signal circuits may be desirable either for the purpose of providing for successive formulation of signals in two separate circuits when boxes of the so-called succession type in the respective circuits are concurrently started, or for the purpose of actuating signal manifesting devices such as gongs or registers in such circuits. It is therefore a further object of the invention to provide a signaling system of the type referred to, with several signal formulating circuits, the signals of each of which can be repeated in the other similar circuits, and to provide means for preventing the repeating device from influencing the originating circuit with its own signals, which would cause garbling of signals.

Also the invention contemplates the use, in systems of the type dealt with herein, of peculiar alternating current responsive devices producing unidirectional current, with the object of controlling, with alternating current supplied signal loops, receiving and repeating apparatus. operative with direct current, and with the further object of supplying outer signal circuits as Well as direct current operative signal responsive devices With electric energy derived from a source of alternating current.

These and other aspects and objects will be apparent from the following detailed explanation illustrating the genus ofthe invention with reference to several concrete embodimentsthereof. The description refers to drawings, in which:

Fig. 1 is a connection diagram of a signaling system according to the present invention;

Fig. 2 is a similar diagram incorporating instrumentalities for disconnecting faulty signal circuits;

Fig. 3 is a detail of the register incorporated in this circuit;

Figs. 4, 5 and 6 are details illustrating the operation of the register;

Fig. 7 is a connection diagram similar to Fig. 1 but with cut-olf and actuating relays, and illustrating the adaptation of the invention to a reflex repeater circuit;

Fig. 8 is a diagram of a system similar in principle to those shown in the other figures, but adapted for operation with alternating current; and

Fig. 9 is a detail of the alternating current arrangement of Fig. 8.

Fig. 1 shows a comparatively simple embodiment of the invention which is well adapted to illustrate the principle of the invention. In this figure, L denotes a signal circuit or loop with a group of signal formulating stations N, herein referred to as alarm boxes, a current source indicated as a battery I0, and the loop magnet of a signal responsive device or line relay E connected at the central station to the incoming leads ||2 of the loop L. Any suitable number of loops may be employed in order to provide the area served by the signaling system with a sufficient number of boxes, two additional loops L and L" with loop magnets I2 and i3 being shown in Fig. 1. According to the practice common in fire alarm systems, the embodiments of the invention herein described have normally closed loops, signals being formed by interrupting the loop circuits by suitable coding means. However, normally open loops in which signals are formed by closing the loop circuits could be used with this invention.

Each line relay El includes a loop magnet |I, already referred to and controlling an armature constituting a movable switch member 24, a selector contact 2|, and a magnet contact 25. Since the loops are normally closed and the loop magnets Il therefore normally energized, member 24 is normally in attracted position, leaving contacts 25 and 2| open. The central station has a bus 8 electrically joining all switch members 24, and a bus 9 similarly joining all magnet contacts 25. The station has also a current source, herein indicated as a battery B, and, in addition to the line relays E, a selector relay S, a register M, and reception circuit A.

The selector relay S is of the type commonly used as preselector in automatic telephone installations and may have any suitable conventional design. The selector herein indicated comprises a stepper magnet 30 with a vibrator arm 3|, a vibrator contact 32 normally making connection with the arm 3| (the contacts being bridged by a circuit suitable to suppress sparking), in series with the magnet, a number of line contacts l, 2, 3, etc., one line contact being provided for each loop, and a wiper 35 which is in well known manner mechanically or otherwise controlled by armature 3| so that it moves over the line contacts step by step so long as magnet 30 remains energized, thereby consecutively connecting the contacts with the selector lead 36. In well known manner, the wiper progresses always in the same direction and, having a sliding contact at each end, again touches the rst line contact with one of these two sliding contacts after the other sliding contact has left the last line contact.

The register M is of the so-called open circuit type, as for example described in connection with Fig. 14 of Patent No. 1,602,065 of October 5, 1926 to C. El. Beach. As at length described in that patent, a register comprising relay mechanism of this type has a paper feed mechanism (not shown) which is automatically started when magnet 3|3 is energized and continues to run a certain period of time, usually somewhat longer than the longest interval between the impulses of any signal, following each energization of the magnet 3|3, as will be apparent from the following explanation of the operation of this circuit. A pivoted member 3| of insulating material, associated with the feed mechanism, is moved quickly in one direction by a spring 3|2 whenever it is released due to energization of magnet 3| 3, whereupon it is slowly restored to normal position by the feed train. The register is so arranged that normally closed contacts |95 and |99 of the register switch (contact |95 having a follower cooperating with a notch of member 3| l), open immediately upon energization of the magnet and are reclosed just prior to termination of the run of the paper feed train. It is understood that relay M must not necessarily comprise a paper feed train and devices for recording signals on a tape, but that any apparatus for operating a switch in the above described manner can be used.

The reception circuit A comprises reception circuit conductors and 46 connected to wiper lead 36 and station battery B, respectively, and signal repeating devices such as tape recorders, goings, or any other suitable recording, acoustic, or optic signal manifesting means, which are indicated at 50.

As shown in Fig. 1, the line selector contacts 2|, 22, 23, etc. of line relays E are connected with line contacts I, 2, 3, etc., respectively, of the selector relays, by means of conductors 4|, 42, 43, etc. Stepper magnet 30 and vibrator contact 3| are connected intermediate bus 9 and register contact |96 through conductors 31 and 38, respectively, whereas contact |95 of the register switch is joined to battery B by lead 39. ister magnet 3|3 is connected between reception circuit conductors 45 and. 46. with leads 48 and 49.

This circuit operates as follows: Upon interruption of any one of the loops, for example i loop L, due to signals being despatched from an alarm box, or perhaps due to an accidental break, magnet of the loop becomes deenergized and drops switch member 24, thereby connecting bus 8 and battery B with magnet contacts 25 and the respective selector contact, for example, 2|. Contacts |95 and |96 of register M being closed, stepper magnet 20 is energized through circuit B-8-24--25-9--31- 30-3 |3238| 96| 95-39-B, and begins to rotate wiper 35 which in due course reaches the line contact corresponding to the interrupted loop, in the present instance, contact l, no matter what its prior position was. With the customary rates of code signal impulses used in this Reg- I type of installations, and with the switching speed of commercially available telephone preselector switches, the Wiper is able to cover the whole range of line contacts during the shortest interval between signal impulses, so that contact I is securely reached before the loop Vis again closed and contacts 2l and 24 broken in the course of signaling.

When the wiper has reached contact I, register magnet 3| 3 is energized through circuit B-S- 24-2 I 4 I I -35-3 6--49-3 I348-B, starts thepaperfeedtrain of the register and causescam 3II to rotate, thereby opening contacts |95, ISB. These contacts being in the energizing circuit of the stepper magnet 39, the selector switch is stopped and the connection between signaling loop L and reception circuit maintained. Since the time elapsing from energization of magnet 3I3 to the opening of switch I 95-I 96 is shorter than that needed by the stepper magnet to move the wiper from one line contact to the next, the connection is always established at the proper contact, in this case contact I. Signals can now be received through the operation of line relay E dropping and attracting its switch member 24 as the loop L is interrupted and again closed, member 24 energizing and deenergizing the reception circuit through selector Contact 2I. The signals are, for example, recorded by register M, or manifested at other devices connected to reception circuit A. Upon running down of the register feed train after completion of a signal, as above explained, contacts and I 98 close and the device is again ready for signal reception from any one of the loops, member 24 having been in the meantime attracted, interrupting contacts 25 and 2| and therebydeener gizing magnet 3I3.

If one loop, for example L', should be interrupted when another loop, for example L, despatches signals, the wiper stopping at line contact I can not proceed to line contact 2, corresponding to L', before the signal from L is nished,because of the interruption of the energizing circuit of Stepper magnet 3|) at register contacts ISS-|96.

If a loop, for example L', should remain open indefinitely, as in the case of an accidental break in the loop circuit, the wiper 35 of switch S will be stepped around until it makes contact with line contact 2. Register M will then be tripped, thereby opening contacts IE5 and ISE and thus preventing further movement of wiper 35. After a predetermined cycle of operation, register M again closes its contacts I 95 and I 96, thereby again energizing magnet 3B of switch S, and stepping wiper 35 out of contact with line contact 2. This interrupts the path through register magnet 3 I3 and thus restores the register to normal condition. Magnet 30 continues to step Wiper 35 until it either finds another loop circuit open or until it again makes contact with line contact 2. If no other loop is open, the register M will again be tripped and the cycle described above will be repeated until loop L is restored to normal closed circuit condition, or until the driving power for the register is exhausted.

Whereas circuits according, or similar, to Fig. 1 are suitable for use in installations with central stations which are permanently supervised, the operator disconnecting any signal loop which remains open indefinitely, modifications similar to Fig. 2 are preferable where constant supervision is not contemplated, so that the repeating mechanism should respond only to sound signal loops regardless of the presence of faulty loops, without the necessity of manual readjustment.

The embodiment shown in Fig. 2 has signal loops L, line relays E, a station bus 8, a selector relay S, a station battery B, and reception circuit A- similar to the' corresponding elements of Fig. 1, designated with like numerals. The register P is somewhat different from register M vof Fig. 1 and comprises two sets of contacts,

one of which is normally closed and opens upon energization of the register magnet, staying open for a predetermined period, whereas the second set of contacts is normally open andv closes only for a very short time immediately before the first I ledge |25, gear train H8, and escapement I23.

Upon energization of magnet IUI, armature ID3 releases arm IM which in turn releases ledge `#L5 and therefore the movement, so thatcam IM begins to rotate, returning arm |04 to nor mal position and quickly depressing lever II4,1-" -which is permitted by the ratchet device of gear train II8. After lever H4 is released by cam IZ, it can return only slowly into initial position, due to escapement I23, which is now connected to segment IIS by the ratchet device.- f Pin` 5I of lever H4 actuates two switches, a normally open restoring switch with spring contacts 52 and 53, and a normally closed register switch with contacts 54 and 55. The contacts 52 and 53 and their function are schematically shown in'Figs. 3, 4, 5, and 6, as follows: As indicated in Fig. 3, spring contact 52 has an extension 56 for engagement with pin 5I, which, however, clears the body of spring 52. Upon descending,

pin 5I first releases spring contact 55, thereby? interrupting connection between- 54 and 55. Later (Fig. 4) it engages extension 56 at the inside,'slides down 56, and leaves it again, thereby releasing 52 into initial position (Fig. 5). The electrical relation of contacts 52 and 53 isl thereby not inuenced. Upon moving upwardly, pin 5I engages the outer side of extension 56 and presses 52 towards 53, establishing contact during the'engagement between pin 5I and extension 5E, whereupon 52 and 53 separate again and shortly thereafter, pin 5I recloses contacts 54 and 55. Similar to the operation of register M of Fig. 1, the feed train of register P is so timed that contacts 5G, 55, opened upon initial energization of magnet lill, reclose only after the4 lapse of a period somewhat longer than the longest interval between signal impulses.

Each loop L, L', etc., is associated with a restore relay D, D', etc., each restore relay having a restore magnet 5I Vcontrolling two normally closed switches 62 and 63, herein referred to as stepper magnet switch and cut-off switch, respectively, and a change-over switch 64. As shown in Fig. 2, one contact of switch 62 is connected to one terminal of magnet 6I, whereas the other magnet terminal leads to the movable element of changeover switch Si! which normally connects the magnet with a contact 55, herein called energizing contact, but which contacts with contact 55, herein referred to as holding contact, upon being attracted by 6I. As schematically indicated in Fig. 2, this change-over switch should be so arranged that when the movable member 64 is attracted by 6I, it will make contact with 66 before breaking contact with'65..;75

iis

-magnet 30.

` lAs shown in Fig. 2, movable members 24 of line relays E lead toy station bus 8, whereas selector contacts 2|, 22, etc.,.are connected to the respective cut-oir switches 63 of their restore relays,

and magnet contacts 25 to their respective magnets 6|. The station has conveniently three additionalbusses 1|, 12, 13, bus 1| being connected to the pole of battery B which is also joined to reception circuit bus 4B. Bus 1I also electrically joins all holding contacts 66. The movable members of allstepper switches 62 are connected to bus 12, which leads to one terminal of stepper Bus 13, electrically joining all energizing contacts 65, leads to Contact 53 of the restoring switch of register P. Each cut-ofi' switch 63 leads to thecorresponding line contact of the selector relay S, Fig. 2 showing the cut-off switch corresponding to loop magnet II connected to line contact I, and the cut-o switch corresponding to magnet I2 connected to line Contact 2.

Similar to the embodiment of Fig. 1, wiper 35 leads to reception circuit conductor 45, register magnet IDI is connected intermediate the wiper and the'battery, in parallel with the reception circuit, and register switch 54-55 normally conneots/ the battery with vibratorv 3|, 32 of selector relay S. Contactv 52 of the normally open restoring switch of register P` is also connected to the battery.

` The circuit shown in Fig. 2, with an individual restore relay for each loop, operates in the following manner. As described before, the line relay E' of an interrupted loop, for example loop L, drops member 24, connecting` the battery with contacts 2| and 25. This closes a circuit B-8 24--2 5 8 2--1 2 30-3 I 3 2-54-5 5-46 B, which energizes stepper magnet 30, thereby starting theA selector switch. Wiper 35 having made contact with the respective linev contact, in the present example contact I, establishesV a circuit B 8 2 |63I3545|0 |-46 B which energizes register magnet IBI. Register P starts its feed train and immediately opensr contactsr 54, 55, thereby arresting'the'wiper of the selector switch at line contact I, connecting with selector contact 2|. The above-described registering means are nowready to receive signals from outer circuit L, through interruption of contact 2| of line relay E responding to signaling impulses. After the signal has been received and the register movement nearly run down, contacts 52, 53. close momentarily, as hereinbefore described, thereby closing a circuit B--8-24-2 5-6 I-SII- -13L-53-52-4`5--B and energizing restore magnet E which attracts switch members B2, 63 and 54, changing 64 from energizingY contact 65 to holding contact 6G and opening stepper and cut-ofi switches 62 and 63, respectively. This establishes a holding circuit B-1I-66-64- 6|-25-24-8-B for magnet 6|, so that |2` and 63 are retained open soflong as line magnet II remains deenergized, member 24 droppedand 25 closed. If, therefore, any one loop should not become normally closed upon having transmitted a signal, but remain open for an undetermined time, as perhaps due to a break, its restore relay D restores responsiveness of the repeater with respect to the remainder of the loops, whereas the faulty loop is excluded from influencing the signal manifesting circuit so long as it remains open. Upon reclosing it, energization of loop magnet I I and lifting of member 24 ensues, opening the holding circuit of restore magnet 6| at 25, so that members 62, 63, and 64 return to normal position, enabling the repaired loop again to actuate the repeating devices. It will be understood by any one skilled in the art that alarm devices can be introduced, for example, in connection with members |52v and 63, vfor indicating at the central station or elsewhere that a loop is faulty and requires attention.

Fig. '1 shows a modification similar to the circuit of Fig. 1,*but of the reiiex type and performing additionalfunctions. As in Fig. 1, there are loops L, L', L", etc., in which the signal formulating stations N are of the so-called non-interfering and succession type or in which signal manifesting devices as, for example, gongs G, are included, and a station with line relays E, battery B, busses 8 and 9, reception circuit A, and a selector relay'S. There are in addition a cut-off relay C, an actuating relay F, and a reflex relay R.

The cut-oir' relay C is somewhat similar to the restore relay D shown in Fig. 2, and has a cut-of magnet 8| controlling a step-per magnet switch'82 with stepper contact 83 and a changeover switch 84 with cut-off contact 85 and holding contact J86. Switch member 84 is connected to one terminal of 'magnet 8|, and contact 86 and stepper switch member 82 are electrically joined.

The selector relay S is similar to relay S of Fig. 1 but has auxiliary short-circuiting switches here indicated by two sets of auxiliary line contacts I', 2', 3', etc., and I, 2, 3", etc., corresponding to line contacts I, 2, 3 etc. of the main selector switch, and two auxiliary wipersk 35 and 35", mechanically or otherwise associated with wiper 35 for conjoint movement and electrically joined' by conductor 48.

Actuating relay F has an actuating magnet 9| and normally open spring contacts 92, 93 vwhich close quickly upon energization of magnet 9| and open again a predetermined time after the last preceding energization of 9|. Any mechanism suitable to perform this function may be employed. Fig. '1 shows, as an example, the following arrangement: A lever 94 is pivoted at 95 and has linked thereto'armature 95 and catch 91. A toothed segment 98 is also pivoted at 95 and has a hook 99 adapted to be engaged by catch 91,. An escapement and ratchet device |90 permits quick rising of segment 98, but only a slow dropping thereof. If magnet 9| is deenergized, contacts 92 and'93 are separated by insulating block 90 of segment 98. If 9| becomes energized, lever 94 quickly lifts segment 98, permitting contacts 92 and 93 to close. Arrived in elevated position, catch `91 strikes stop |92 and releases hook 99 of segment 98 which thereupon beginsto drop slowly, and' at its lowest position again separates the switch contacts. Upon deenergization of magnet 9|, lever 94 drops, its catch 91 reengaging hook 99. It is apparent that contacts 92 and 93 always reclose after a predetermined time from the last energization of magnet 9|, no matter whether or not `segment 98 has partly dropped between two energizations.

The reex relay R has .areflex magnet |39 which controls, a series of normally closed reflex switches I3I, |32, |33, etc., one for each signal loop.

Asin Fig. l1, the members 24 of line relays E are interconnected by bus 8, and" their magnet contacts 25A by bus:9. Selector contacts 2|, 22, 23, etc., are connected to the corresponding line contacts I, 2,'3, etc., of the selector'relay S. Reiiex switches 3| |32, |33, etc., are serially included in the signal loops through conductors 23|, 232; 33|, 332 and 43|, 432 respectively, the loops remaining closed so long as the reflex switches remain in their closed position, that is, so long as reflex magnet |30 is deenergized. By means of conductors 233, 333, 433; 234, 334, 434, auxiliary line contact pairs l, 2', 2, 3', 3", etc., are connected in parallel to respective signal loops, short circuiting reflex switches |3|, |32, |33, etc., respectively, upon being bridged by wipers 35', 35" and conductor 48.

Actuating magnet 9| of actuating relay F is connected between bus 9 and one pole or battery B, and actuating switch contacts 92, 93 between the other pole of B, and, through conductor |4|, to the movable member of stepper magnet switch 82 and to the holding contact 86 of cut-off relay C. The stepper contact 83 and vibrator contact 32 of stepper magnet 38 are joined by conductor |42, and cut-01T contact 85 of cut-off" relay C is connected to conductor 45 of the alarm circuit and therefore to wiper 35. Cut-off magnet 8| is connected intermediate, therefore, to change-over switch 84 and battery B, by means of conductors 89 and 48.

Reex magnet |38 is connected between the reception circuit conductors 45 and 46 and may be in series with other suitable signal responsive devices, as indicated by apparatus 58, or may be connected independently in parallel to such responsive devices, as indicated at |58.

The reflex repeater circuit of Fig. '1 operates in the following manner, As previously described, the interruption of a loop, for example L, causes members 24 to drop. Contact 25 closes a circuit B-8-24-25-9-9I-B, energizing magnet 9| of actuating relay F, which thereupon promptly closes contacts 92, 93. This establishes a circuit B 92-83- 4 |-82-83-32--3 |-38-B which energizes stepper magnet 38, actuating the selector relay, whose wiper 35 advances until reaching line contact At this moment, a circuit B--8-24- 2 I- |-3 5-85--84-8 |-8 9-46-B is established, energizing cut-off magnet 8| which attracts switch members 82 and 84, opening contact 82, and changing connection of 84 from 85 to 86. This establishes a holding circuit B-9293 I4|86848|8948B for magnet 8| and breaks the energization circuit of stepper magnet 38, thereby stopping wiper 35 at contact I, which establishes association between loop L and reception circuit A. At the same time, cut-01T magnet 8| is disconnected from circuit A.

The reception circuit is now enabled to repeat any signal despatch from L, and such signals are also reflexed into the other loops, but not into L, in the following manner. Reflex relay Ris connected across the reception conductors 45, 46, and its magnet |38 is energized every time loop L is interrupted and selector contact 2| connected to member 24. The reex magnet then opens switches |3|, |32, |33, thereby correspondingly interrupting loops L and L" and actuating any signal responsive devices G which may be included in the loops. When wiper 35 connects contact with reception circuit conductor 45, wipers 35 and 35" rest at contacts and I", conductor 40 connecting these two contacts and therefore shortcircuiting switch |3|, so that signaling loop L is not affected by the opening of switch |3| of the reilex relay.

A predetermined time after loop L has stopped signaling, that is, a certain period after magnet 9| of actuating relay F has lastbeen energized,

segment 98, by dropping, again opens contacts 92 and 93, thereby opening the holding circuit of magnet 8| and therefore restoring the whole circuit `to normal condition, ready to receive and to repeat subsequent signals from any one of the loops.

If two loops, for example L and L', should despatch signals simultaneously, it might happen (assuming the absence of actuating relay F, and that L starts signaling subsequently to L) that L begins to repeat in the middle of one of its signal groups, immediately following the last signal group of L, which could easily cause misinterpretation of signals. However, actuating relay F maintains contacts 92, 93 closed, cut-off 8| energized, and therefore stepper contacts 82, 83 open during a certain time interval after loop L has stopped signaling. Hence, stepper magnet 38 can not be energized before that time, wiper 35 can not connect contact 2 to the alarm circuit, and signals from L can not be repeated until an interval has elapsed that is sufficient for separating the signals of L and L.

If this time interval is chosen a trifle shorter than the longest interval within any one series of signals (this longest interval being the socalled round pause), but longer than any other signal interval, the signals of the subsequently signaling loop L are repeated commencing with the start of a complete round.

In case a loop, for example L, is accidentally broken and magnet permanently deenergized, magnet 9| remains energized, but contacts 92, 93 nevertheless open after a certain time, breaking the holding circuit for magnet 8 I, which will then vibrate since wiper 35 is still at contact and thereby holding the energizing circuit for 8| closed. Stepper magnet 38 is at the same time disconnected, sothat no other loop can possibly transmit signals so long as one loop is abnormally interrupted. Relay C keeps vibrating, indicating the faulty condition, until loop L is repaired or member 24 of magnet manually lifted, thereby separating loop L from the installation.

The modification shown in Fig. v8 and claimed in Patent No. 2,040,288 of May 12, 1936 utilizes a circuit similar to, but somewhat simpler than that of Fig. '1, its signal loops being supplied with alternating current. In certain instances it may be desirable to use alternating current in the outer signaling circuits, but, station equipments being usually not well suited for operation with such current, an arrangement like that to be described is preferable and useful in such instances, since it permits the use of the customary direct current station apparatus.

The loops L with alarm boxes N are supplied with alternating current of suitable voltage and frequency from supply busses |2|, |22, through supply transformers ||8. Each loop has a line transformer T with primaries |5|, |52 having terminals |58 and |59 on either side of tap |50. An adjustable impedance |55 is provided which reproduces the electric characteristics of loop L. Secondary |58 of supply transformer ||8 is connected between tap |58 and terminal |10 of the impedance |55, loop L is connected between terminals |18 and |59, and impedance |55 between terminals |58 and |18. It is apparent (especially from Fig. 9, which groups these elements in a somewhat simplified, but equivalent manner), that the electromotive forces of primaries |5| and |52 balance each other, provided that the primary windings and loop L and impedance |55, respectively, are electrically substantially equivalent, in which case no electromotive force is induced in secondary |60 of transformer T, so long as the loop is closed.

Secondary 60 supplies the input terminals I6 |62 of rectifier bridges |63, |66 of conventional design, supplying output terminals |66, |61 and |68, 1| respectively, with unidirectional current, if an electromotive force is impressed in secondary |60. In Fig. 8, terminals |66, |61, |68 of all line transformer circuits are denoted with these like numerals, whereas the fourth terminals of the loop have numerals |1|, |12, etc. All terminals |66 and |68 are joined by bus 8 and all terminals |61 are joined by bus 9, whereas terminals |1|, |12, etc., are connected to corresponding line contacts 2, etc. of selector relay S.

Selector relay S, cut-off relay C, and reception circuit A are similar to the corresponding devices shown in Fig. '7, but somewhat differently connected, as will be explained hereinafter.

Register M has normally open contacts 295, 296 and a paper feed train, and switch operating devices quite similar to those of register M incorporated in the circuit of Fig. 1, with the difference that contacts 295, 296 are normally open and close effectively only for a short time just before the feed train terminates its run. As shown in Fig. 8, block 3H, quickly turned by spring 3 2 upon energization of magnet 3 I3, closes at that time the contacts during a period which is so short as to have no influence upon the circuit, whereas, towards the end of the slow return movement of 3| l, it closes contacts 295, 296 for a time which is sufficient to effect the desired result Which will appear hereinafter.

Stepper magnet 39 is connected intermediate bus 9 and stepper magnet switch 82, which normally connects it with bus 8 through conductor 46, and also with one terminal of cut-off magnet 8|. The other side of the magnet 8| is connected, through resistance |13, to change-over switch 84 which connects it normally to wiper 35, through alarm circuit conductor 45. The holding contact 86 is connected to the positive terminal of a local rectifier |14. The negative terminal of that rectifier is connected through conductor 46 to the bus 8, and the input terminals are connected to the alternating current supply busses |2| and |22. Magnet 8| can be short circuited by normally open contacts'295, 296 of the register M whose magnet 3|3 is connected between conductors l5 and 46.

'Ihe arrangement shown in Fig. 8, especially suited for operation with alternating current, but

' in principle an adaptation of the circuit of Fig.

l, with a cut-off relay added and employing instead of the line relays E what may be called, for want of a better term switchless alternating current relays, which have been described hereinbefore, operates as follows: Under normal conditions, when the loops L, L', etc., are closed, the electromotive forces of the line transformer primaries |5I, |52, supplied from busses |2|, |22, balance one another and no electromotive force is induced in |60, so that the station circuit does not carry any current. Upon interruption of a loop, say L, connection between |59 and |16 is broken, |5| carries no current, and the electromotive force of |52 produces a current in the supply circuit of rectifiers |63 and |66, so that unidirectional electromotive forces appear across terminals |66, |61, and |68, |1| respectively. The unidirectional potential across` busses 8 and 9 supplies current to circuit 8-46-82--3l-32- 39-9 which energizes stepper magnet I36, the

lconnected to the alarm circuit.

latter advancing wiper 35funtil it touches line contact At this moment, a circuit |68-8-46- 8|-I13-84-85--65-35-I--IH is closed, energizing cut-off magnet 8| which attracts its armatures 82 and 612, opening the above traced stepper magnet circuit at 82, and changing member 84 from cut-off contact 85 to holding contact 86. This action instantly interrupts the stepping action of magnet 30, arresting the Wiper at the appropriate line contact and establishing a holding circuit negative terminal of rectifier |15-66--8l-l13-84-86--9 for cut-01T magnet 8|, so that no other loop can interfere with the signaling loop L during energization of 8|. After loop L has finished its signal, that is, shortly before the feed train of register M has run down, contacts 295, 296 are closed, shortcircuiting magnet 8|, which thereupon releases members 82 and 8d, restoring the circuit to normal condition. The resistance |13 prevents shortcircuiting of the rectifier |14 during such closure of contacts 295 and 296.

During the signaling period, signals are received at register M', or other apparatus, as 50,

The unidirectional current furnished by rectifier bridge |64 upon interruption of the respective loop corresponds to the current of battery Bof the other figures, there made available by the closing of selector contact 2|, and unidirectional current furnished by rectifier bridge |63 corresponds to the direct current from battery B made available through contacts 25. Unidirectional current is al-so furnished by the rectifier bridge |14 for the holding circuit of relay C. In this manner, a signaling circuit supplied With alternating current exclusively is provided, which combines the advantages of signal loops energized with alternating current and of a repeater circuit operated with unidirectional current, without involving the use of relays and local supply batteries.

If any one of the loops, for example loop L, remains open indefinitely, the contacts 295 and 296 of register M will cause momentary deenergi Zation of magnetiil and during such deenergization of 8|, contacts 82 will close the circuit through magnet 36 and cause stepping of wiper 35. If no other open loop circuit'is found, wiper 35 continues to step around until it again arrives' at contact where it again stops vand causes a second actuation of register M'.

This action is repeated continuously so long as` loop L remains open, thus calling the operators attention to the faulty condition of the system, which can be rendered responsive to the sound loops by manually interrupting the rectifier output leads of the faulty loop.

It will be evident to anyone skilled in the art that the different features of the embodimentsv herein described can be combined in various ways,

as for example, that any of these circuits can be' equipped with reflex repeating equipment, as shown in Fig. 7, and operated with either direct current or with alternating current, as shown in Fig. 8.

t should be understood that the present dis-v ply upon interruption of the respective loop with a magnet contact and a selector contact; a selector relay including a stepping magnet, a series of line contacts and a wiper actuated by said stepping magnetthe magnet being connected to all of said magnet contacts, each line contact being connected to a respective one of the selector contacts, and the wiper being connected to said conductor; and an open circuit register for visually manifesting signals and having a time train with a controlling register magnet therefor intermediate said conductor and said supply, and a normally closed register switch intermediate said stepping magnet and said source opening upon energization of said registerl magnet and closed by a predetermined run of said time train following energization of said register magnet, said selector relay being actuated by said stepping magnet selectively to associate the line relay of an interrupted loop with said conductor, and retained in connecting position b y opening of said register switch which deenergizes said stepping magnet upon energization of said register magnet after said selector relay has selected the line contact corresponding to the interrupted loop.

2. A signaling system of thev character described comprising a current supply; a reception circuit conductor; normallyy closed signal loops each including a line relay with a magnet contact and a selector contact, both contacts being connected with said supply upon interruption of the respective loop; a selector relay including a stepping magnet; a multiple contact selector switch actuated thereby and connected to said conductor; a register for recording and visually manifesting signals, said register including a register magnet connected intermediate said conductor and said source, a normally closed register switch intermediate said stepping magnet and said supply and opened bysaid register magnet during signal receiving periods, and a normally open restore switch momentarily closing towards the end of said periods; and a restore relay for each loop, each restore relay having a normally deenergized restore magnet connected intermediate the magnet contact of its loop and said source through said restore switch and controlling a stepper switch normally connecting said magnet contact with said stepping magnet, a cut-oil` switch normally connecting the selector contact of the respective loop with a corresponding contact of said selector switch, and a holding circuit, including said magnet contact, for said restore magnet, said register switch arresting said selector relay upon reaching the line contact corresponding to an open loop, and said restore switch energizing said restore magnet a certain time after energization of said register, thereby causing said restore magnet to maintain said stepper switch and said cut-01T switch open until said line relay opens said magnet contact upon reclosing of said loop.

3. A signaling system of the character described comprising a current supply; a reception circuit conductor; normally closed signal loops each including a line relay with a magnet contact and a selector contact, both contacts being connected with said supply upon interruption of the respective loop; an actuating relay having an actuating magnet energized through said magnet contact, and a normally open actuating switch closed upon energization of said actuating magnet, said actuating relay including means for maintaining said actuating switch closed for a predetermined time; a selector relay having line contacts connected to. corresponding' selector contacts, respectively, azstepper magnet, and` awiper actuated by said stepper magnet and connected to said conductor; a cut-off relay having a cut-off. magnet controlling a normally open holding circuit closed' upon energization of said cut-oil'` magnet, a normally closed stepper magnet vswitch adapted serially to; connectv said stepper magnet and said' actuating switch across said supply, and a cut-01T contact normally connecting` said cutoff magnet intermediate said. Wiper andv said supply;

4. A. signaling system of theA character described, comprising a. current. source; a` plurality of. signal loops each having. a signal formulating. meansl and a. signal responsive relay; a selector switch having av contact for each loop, a signalv reception device and ar normally closed cut-olf` switch in areception circuit; an actuating means; for; said` selector switch,v a normally closed circuit breaker and a` normally open switch in an actuating circuit. connected to said source; means associated with each relayv for connecting a contact of said selector switchwith said source upon response of a relay to abnormal, conditioning; of, its loop, means for closing said normally open switch upon response of said relay and opening; it a predetermined time thereafter; and means for opening said reception circuit and said circuit breaker upon connection of said contact with said source until said switch reopens.

5. A signaling system of the character described comprising signal loops; a reception circuit; loop selecting means adapted consecutively to associate each of said loops with said circuit; meansy includingv a. time train for effecting actuation of, said selecting means upon abnormal conditioning of one of said loops; and cut-off means for instantaneously arresting said selecting means. when it has estab-lished association between an abnormal loop and said circuit, said actuationeffecting means. maintaining said cutoff means eifective for arresting said selecting means throughout a predetermined run of said time train from the beginning of said abnormalv condition.

6. A signaling system of the character described comprising a plurality of signal loops each having means for formulating code signals comprising groups of impulses; a recording device for visually manifesting signals, said device having electromagnetically controlled mechanism responsive to signals formulated in any of said loops; control contacts, associated with said recording device, and abnormally conditioned by said mechanism in certain predetermined time relation to the response of the mechanism to the iirst and last impulses of any such signal; a selector switch having a plurality of selector contacts, one for each of said loops and a stepping magnet in series with said control contacts and establishing connection at the selector contact associated with any one of said loops in response to the first signal impulse formulated in said loop; a current sour-ce for operation of said recording device and said stepping magnet; and means for actuating said selector switch in response to a rst signal impulse to associate said recording device through said selector contact with the loop in which formulation of said impulse originated and with said source, for response to such signal, said control contacts supervising said stepping magnet for maintaining said association effective throughout, and for a predetermined time following, the formulation of said signal.

7. A signaling system of the character described comprising a plurality of signal loops each having means for formulating code signals cornprising groups of impulses; a recording device for visually manifesting signals, said device having electromagnetically controlled mechanism responsive to signals formulated in any of said loops; normally closed control contacts associated with said recording device, and opened by said mechanism in response to the iirst impulse of any such signal and hel-d open by said mechanism until after the expiration of a predetermined interval following response of the mechanism to the last impulse of said signal; a selector switch having a plurality of selector contacts, one for each oi said loops and a stepping magnet in series with said control contacts establishing connection at the selector contact associated with any one of said loops in response to the first signal impulse formulated in said loop; a current source for operation of said recording device and said stepping magnet; and means for actuating said selector switch in response to a i'lrst signal impulse to associate said recording device through said selector contact with the loop in which formulation of said impulse originated and with said source, for response to such signal, said normally closed control contacts supervising said stepping magnet for maintaining said association effective throughout, and for a predetermined time following the formulation of said signal.

8. A signaling system of the character described comprising signal loops having circuit energizing means made effective upon abnormal conditioning of a respective loop; a current source; a signal recording device having a normally ineiective restore switch mechanically closed at a predetermined time after a reception period preceding the coming to rest of the recording device; loop selecting means including a stepping magnet connected for energization through said energizing means and a selector switch connected to said source through said energizing means in series` with a normally closed l cut oif switch, said stepping magnet moving said seieotor switch upon abnormal conditioning of one of said loops for selectively associating said abnormal loop with said recording device; and a restore magnet connected with said source in series with said restore switch and actuated by said operation of said restore switch to open said cut off switch, thereby disconnecting said selecting meansfor any loop remaining abnormally conditioned for more than said predetermined time.

9. A signaling system of the character described comprising signal loops; a receiving station current source; a signal recording device conditioned for signal reception by a recorder magnet and having a normally closed control switch opened-at the energization of said magnet and a normally open restore switch momentarily closed a -predetermined time after each signal reception period; for each loop a line relay having a magnet contact and a selector contact both connected to said source upon abnormal conditioning of their respective loop; for each loop a restore relay including a restore magnet between said magnet contact and said restore switch, a normally closed stepper switch and a normally closed cut olf switch in series with said recorder magnet and said selector contacts of said line relay respectively, and a holding circuit for said restore magnet including said magnet contact; and a selector switch having a plurality of contacts one for each of said loops, and a stepping magnet in series with said selector contact, said control-switch and said stepper switch; said selector switch connecting in response to abnormal conditioning of one of said loops said recorder magnet with the'selector contact of said abnormal loop, said recorder magnet, by opening said control switch,-arresting said selector switch at the Contact associated with said abnormally conditioned loop for signal reception by said recording device, and said restore switch actuating at said predetermined time said restore magnet causing it to disconnect said abnormal loop by opening its stepper and cut off switches.

FOSTER E.r WELD. 

